It is known to treat plant growing soil with fumigants to prevent the harmful effects of invasive weeds and other unwanted vegetation and pathogens. If allowed to grow, these invasive plants would compete with the agricultural crops for water, minerals and sunlight. They would increase stresses from nematodes, insects and disease, and adversely affect product quality. Also, harvest efficacy is diminished due to pickers inability to find and pick produce in weedy growth. Unwanted vegetation increases production costs by adding control costs up to several hundred dollars per acre.
Methyl-bromide (M-b) has been the most effective fumigant for agricultural and ornamental plant applications. M-b is usually applied by one of two methods. The first and most popular method is called “flat field” fumigation. The ground is prepared for bed-making and is irrigated lightly to induce weed seeds to become more active or “viable” and thus more susceptible to the penetration of the poison gas. Then the M-b gas is applied to the flat, level soil by injection equipment mounted on tractors. Simultaneously, the gas is sealed in the soil beneath solid plastic sheeting which is provided as a cover over the soil. Tractors carry large pressurized cylinders of M-b gas and rolls of clear plastic sheeting (e.g., 4 mil thick and 12 feet wide). These tractors pass across the field and inject the M-b about twelve inches deep into the soil. Injection shanks are designed to release the gas in a way that prevents it from escaping the soil too rapidly. The plastic sheeting unrolls from the rear of the tractor as gas is applied and the sides of the sheeting are continuously buried to seal the gas below the plastic. The plastic sheets are left sealed for at least six days to allow the gas to dissipate to safe concentrations. Then, the plastic is removed and discarded. The agricultural beds are made and new plastic sheeting is laid out on top of the beds.
The second method of fumigation has been named the “bed fume” method. It involves making the beds first (e.g. about 64 inches wide) and then injecting the M-b gas into each individual bed. Plastic sheets are stretched across the beds and buried, using the same tractor that injects the gas. These beds are ready for planting after sitting for six days. The fumigation plastic cover is left on the bed and becomes the bed mulch.
Many countries are restricting or eliminating the use of M-b because it is now labeled as an ozone depleting substance. Other alternative fumigants have been tried without success.
There is a need for a way of suspending undesirable plant growth without using a substance that adversely effects the desirable plant growth and/or the environment. This substance must effectively suspend the undesirable plant growth without harming the agricultural or ornamental crop that is planted or growing in the soil, and without harming the environment.